This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Type 1 diabetes mellitus (T1DM) is one of the most common and serious chronic diseases in children, particularly in the very young. The etiology of the disease remains unclear. There is a substantial genetic component to susceptibility to T1DM. High risk HLA class II alleles appears to contribute 40-45% of genetic risk and other genes have been identified as providing more modest contributions to risk. Only about 1 in 15 children in the general population with the high risk HLA alleles and one in five with a first degree relative with type 1 diabetes and with the high risk HLA will develop T1DM. Epidemiologic patterns suggest that viruses, nutrition, toxic agents or socioeconomic psychosocial factors may contribute alone or in combination. Definitive identification of environmental factors that precipitate T1DM has proven difficult. The long-term goal of this NIH-funded TEDDY study is the identification of infectious, dietary, or other environmental exposures and psychological factors which trigger or prevent T1DM in genetically susceptible individuals. We will study from birth, high-risk children from the general population and relatives of people with T1DM for exposures to candidate environmental factors. Over 200,000 newborn babies will be screened by 6 centers in the US (Florida/Georgia, Colorado, Washington state), Finland, Sweden and Germany. Identification of such factors will lead to a better understanding of the cause of T1DM and could result in new strategies to prevent, delay, or reverse T1DM.